1
|
Frascaroli G, Lecher C, Varani S, Setz C, van der Merwe J, Brune W, Mertens T. Human Macrophages Escape Inhibition of Major Histocompatibility Complex-Dependent Antigen Presentation by Cytomegalovirus and Drive Proliferation and Activation of Memory CD4 + and CD8 + T Cells. Front Immunol 2018; 9:1129. [PMID: 29887865 PMCID: PMC5981096 DOI: 10.3389/fimmu.2018.01129] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2017] [Accepted: 05/04/2018] [Indexed: 12/28/2022] Open
Abstract
Human cytomegalovirus (HCMV) persistently infects 40–90% of the human population but in the face of a normal immune system, viral spread and dissemination are efficiently controlled thus preventing clinically signs and disease. HCMV-infected hosts produce a remarkably large amount of HCMV-specific CD4+ and CD8+ T cells that can even reach 20–50% of total T memory cells in the elderly. How HCMV may elicit such large and long-lasting T-cell responses in the absence of detectable viremia has not been elucidated yet. Additionally, HCMV is known to encode several gene products that potently inhibit T-cell recognition of infected cells. The best characterized are the four immune evasive US2, US3, US6, and US11 genes that by different mechanisms account for major histocompatibility complex (MHC) class I and class II degradation and intracellular retention in infected cells. By infecting M1 and M2 human macrophages (Mφ) with the wild-type HCMV strain TB40E or a mutant virus deleted of the four immune evasive genes US2, US3, US6, and US11, we demonstrated that human Mφ counteract the inhibitory potential of the US2-11 genes and remain capable to present peptides via MHC class I and class II molecules. Moreover, by sorting the infected and bystander cells, we provide evidence that both infected and bystander Mφ contribute to antigen presentation to CD4+ and CD8+ T cells. The T cells responding to TB40E-infected Mφ show markers of the T effector memory compartment, produce interferon-γ, and express the lytic granule marker CD107a on the cell surface, thus mirroring the HCMV-specific T cells present in healthy seropositive individuals. All together, our findings reveal that human Mφ escape inhibition of MHC-dependent antigen presentation by HCMV and continue to support T cell proliferation and activation after HCMV infection. Taking into account that Mφ are natural targets of HCMV infection and a site of viral reactivation from latency, our findings support the hypothesis that Mφ play crucial roles for the lifelong maintenance and expansion of HCMV-committed T cells in the human host.
Collapse
Affiliation(s)
- Giada Frascaroli
- Institute of Virology, Ulm University Medical Center, Ulm, Germany.,Heinrich Pette Institute, Leibniz Institute for Experimental Virology, Hamburg, Germany
| | - Carina Lecher
- Institute of Virology, Ulm University Medical Center, Ulm, Germany
| | - Stefania Varani
- Department of Diagnostic, Experimental and Specialty Medicine, University of Bologna, Bologna, Italy
| | - Corinna Setz
- Institute of Virology, Ulm University Medical Center, Ulm, Germany
| | | | - Wolfram Brune
- Heinrich Pette Institute, Leibniz Institute for Experimental Virology, Hamburg, Germany
| | - Thomas Mertens
- Institute of Virology, Ulm University Medical Center, Ulm, Germany
| |
Collapse
|
2
|
Subviral dense bodies of human cytomegalovirus stimulate maturation and activation of monocyte-derived immature dendritic cells. J Virol 2013; 87:11287-91. [PMID: 23926346 DOI: 10.1128/jvi.01429-13] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Dendritic cells play a central role in the immune control of human cytomegalovirus (HCMV) infection. This work aimed at investigating the impact of noninfectious, subviral dense bodies of HCMV on the maturation and activation of dendritic cells (DC). Treatment of immature DC with dense bodies led to the maturation of these cells and significantly increased their capacity for cytokine release and antigen presentation. Dense body-activated DC may thereby contribute to the development of antiviral immunity.
Collapse
|
3
|
Lleo A, Invernizzi P. Apotopes and innate immune system: novel players in the primary biliary cirrhosis scenario. Dig Liver Dis 2013; 45:630-6. [PMID: 23415798 DOI: 10.1016/j.dld.2013.01.005] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/16/2012] [Accepted: 01/07/2013] [Indexed: 12/11/2022]
Abstract
Our understanding of primary biliary cirrhosis has been rapidly growing over the past decade and the disease is now regarded as a model for other female-predominant, organ-specific autoimmune conditions. Primary biliary cirrhosis ensues from a multi-lineage loss of tolerance to the E2 component of the pyruvate dehydrogenase complex. One of the major unanswered questions in the pathogenesis of primary biliary cirrhosis is the specificity of small intrahepatic bile ducts attack while PDC-E2 is present in mitochondria of all nucleated cells. Recent findings suggest that the uniqueness of the primary target tissue, biliary epithelium, may be of considerable importance for understanding primary biliary cirrhosis and that the biliary epithelial cell is more than an innocent victim. Rather, it attracts an immune attack by virtue of the unique apoptotic mechanisms and by the way it handles PDC-E2. Moreover, recent evidence suggests that apoptotic bodies of biliary epithelial cell are able to activate the innate immune system in the presence of anti-mitochondrial antibodies. This review article is intended to provide a critical overview of the role of apoptosis in biliary epithelial cells, the activation of the innate immune system, and its biological and clinical significance in primary biliary cirrhosis.
Collapse
Affiliation(s)
- Ana Lleo
- Center for Autoimmune Liver Diseases, Humanitas Clinical and Research Center, Rozzano, MI, Italy
| | | |
Collapse
|
4
|
Gredmark-Russ S, Söderberg-Nauclér C. Dendritic cell biology in human cytomegalovirus infection and the clinical consequences for host immunity and pathology. Virulence 2012; 3:621-34. [PMID: 23076329 PMCID: PMC3545944 DOI: 10.4161/viru.22239] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Human cytomegalovirus (HCMV), a member of the herpesvirus family, establishes life-long persistence and latency after primary infection and can be reactivated later in life. In immunosuppressed patients, it is an important pathogen that can cause severe disease. HCMV is also thought to play a causative role in inflammatory diseases and cancer. The virus can infect different immune cells, including dendritic cells (DCs) and can take advantage of host immune functions to avoid immune recognition. These characteristics have sparked major interest in understanding HCMV and its interaction with immune cells and their relevance to disease pathogenesis. In this review, we focus on the complex host-pathogen relationship between HCMV and DCs, including the persistence of the virus in these cells, their function in the immune response to HCMV infection and the potential clinical consequences of HCMV infection in DCs.
Collapse
Affiliation(s)
- Sara Gredmark-Russ
- Center for Infectious Medicine, Department of Medicine, Karolinska Institutet, Karolinska University Hospital Huddinge, Stockholm, Sweden.
| | | |
Collapse
|
5
|
Folci M, Meda F, Gershwin ME, Selmi C. Cutting-edge issues in primary biliary cirrhosis. Clin Rev Allergy Immunol 2012; 42:342-54. [PMID: 21243445 DOI: 10.1007/s12016-011-8253-3] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Several crucial issues remain open in our understanding of primary biliary cirrhosis (PBC), an autoimmune liver disease targeting the small- and medium-sized intrahepatic bile ducts. These issues include the high tissue specificity of the autoimmune injury despite the nontraditional autoantigens found in all mitochondria recognized by PBC-associated autoantibodies, the causes of the commonly observed pruritus, and the disease etiology per se. In all these fields, there has been recent interest secondary to the use of large-scale efforts (such as genome-wide association studies) that were previously considered poorly feasible in a rare disease such as PBC as well as other intuitions. Accordingly, there are now fascinating theories to explain the onset and severity of pruritus due to elevated autotaxin levels, the peculiar apoptotic features of bile duct cells to explain the tissue specificity, and genomic and epigenetic associations contributing to disease susceptibility. We have arbitrarily chosen these four aspects as the most promising in the PBC recent literature and will provide herein a discussion of the recent data and their potential implications.
Collapse
Affiliation(s)
- Marco Folci
- Division of Internal Medicine, IRCCS Istituto Clinico Humanitas, via A. Manzoni 56, Rozzano, 20089, Milan, Italy
| | | | | | | |
Collapse
|
6
|
Interplay between human cytomegalovirus and intrinsic/innate host responses: a complex bidirectional relationship. Mediators Inflamm 2012; 2012:607276. [PMID: 22701276 PMCID: PMC3371353 DOI: 10.1155/2012/607276] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2011] [Accepted: 03/22/2012] [Indexed: 02/07/2023] Open
Abstract
The interaction between human cytomegalovirus (HCMV) and its host is a complex process that begins with viral attachment and entry into host cells, culminating in the development of a specific adaptive response that clears the acute infection but fails to eradicate HCMV. We review the viral and cellular partners that mediate early host responses to HCMV with regard to the interaction between structural components of virions (viral glycoproteins) and cellular receptors (attachment/entry receptors, toll-like receptors, and other nucleic acid sensors) or intrinsic factors (PML, hDaxx, Sp100, viperin, interferon inducible protein 16), the reactions of innate immune cells (antigen presenting cells and natural killer cells), the numerous mechanisms of viral immunoevasion, and the potential exploitation of events that are associated with early phases of virus-host interplay as a therapeutic strategy.
Collapse
|
7
|
Paracrine inhibition of GM-CSF signaling by human cytomegalovirus in monocytes differentiating to dendritic cells. Blood 2011; 118:6783-92. [PMID: 22031867 DOI: 10.1182/blood-2011-02-337956] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
A primary HCMV infection or virus reactivation may cause severe disease in hosts with a deficient immune system. The virus can disturb both innate and adaptive immunity by targeting dendritic cell (DC) functions. Monocytes, the precursors of DCs in vivo (MoDCs), are the primary targets of HCMV; they can also harbor latent virus. The DCs generated from infected monocytes (CMV-MoDCs) have an altered phenotype and functional defects. We have shown that CMV-MoDCs do not secrete IL-12 in response to lipopolysaccharide stimulation, cannot ingest dead cells, induce T(H)1 differentiation, or the proliferation of naive allogeneic CD4(+) T cells. We found that the GM-CSF signaling in an entire population of CMV-MoDCs was impaired, although only half of the cells were productively infected, and that IL-6 secretion and suppressors of cytokine signaling 3 induction contributed to this bystander effect. We also showed that MoDCs derived ex vivo from monocytes of viremic patients had the same altered phenotype as CMV-MoDCs, including decreased STAT5 phosphorylation, indicating defective GM-CSF signaling. We have thus described a new mechanism of HCMV-induced immunosupression, indicated how infection may disturb both GM-CSF-dependent physiologic processes and proposed GM-CSF-based therapeutic approaches.
Collapse
|
8
|
Lleo A, Shimoda S, Ishibashi H, Gershwin ME. Primary biliary cirrhosis and autoimmune hepatitis: apotopes and epitopes. J Gastroenterol 2011; 46 Suppl 1:29-38. [PMID: 20798971 DOI: 10.1007/s00535-010-0303-8] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/01/2010] [Accepted: 07/28/2010] [Indexed: 02/04/2023]
Abstract
Autoimmune liver diseases (ALDs) represent a wide spectrum of chronic inflammatory diseases that are characterized by an immune-mediated attack against either hepatocytes (in the case of autoimmune hepatitis types 1 and 2, AIH-1, 2) or cholangiocytes (in primary biliary cirrhosis, PBC). PBC is considered a model autoimmune disease due to the homogeneity of patients, the high specificity of antimitochondrial antibodies (AMAs), and the specificity of biliary epithelial cell (BEC) destruction. It ensues from a multi-lineage loss of tolerance to the E2 component of the pyruvate dehydrogenase complex (PDC-E2). One of the major unanswered questions in the pathogenesis of PBC is the specificity of small intrahepatic bile duct attack while PDC-E2 is present in mitochondria of nucleated cells. Recent findings suggest that the apoptosis of BECs may be of considerable importance for understanding PBC, and that they are more than simply an innocent victim of an immune attack. Rather, they attract immune attack by virtue of the unique biochemical mechanisms by which they handle PDC-E2. The role of apoptotic cells in AIH is not well defined, but advances in the study of autoreactive T cells stem mostly from AIH type 2, where the main autoantigen (CYP2D6) is known, enabling the characterization of antigen-specific immune responses. This review article is intended to provide a critical overview of current evidence on tissue specificity in ALDs, as well as the characteristics of the relevant epitopes and apotopes and their biological and clinical significance.
Collapse
Affiliation(s)
- Ana Lleo
- Division of Rheumatology, Allergy, and Clinical Immunology, University of California at Davis, Davis, CA 95616, USA
| | | | | | | |
Collapse
|
9
|
Gugliesi F, De Andrea M, Mondini M, Cappello P, Giovarelli M, Shoenfeld Y, Meroni P, Gariglio M, Landolfo S. The proapoptotic activity of the Interferon-inducible gene IFI16 provides new insights into its etiopathogenetic role in autoimmunity. J Autoimmun 2010; 35:114-23. [DOI: 10.1016/j.jaut.2010.04.001] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2010] [Revised: 04/16/2010] [Accepted: 04/19/2010] [Indexed: 12/22/2022]
|
10
|
Rivas C, Aaronson SA, Munoz-Fontela C. Dual Role of p53 in Innate Antiviral Immunity. Viruses 2010; 2:298-313. [PMID: 21994612 PMCID: PMC3185551 DOI: 10.3390/v2010298] [Citation(s) in RCA: 96] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2009] [Revised: 01/11/2010] [Accepted: 01/19/2010] [Indexed: 01/10/2023] Open
Abstract
Tumor suppressor p53 is widely known as 'the guardian of the genome' due to its ability to prevent the emergence of transformed cells by the induction of cell cycle arrest and apoptosis. However, recent studies indicate that p53 is also a direct transcriptional target of type I interferons (IFNs) and thus, it is activated by these cytokines upon viral infection. p53 has been shown to contribute to virus-induced apoptosis, therefore dampening the ability of a wide range of viruses to replicate and spread. Interestingly, recent studies also indicate that several IFN-inducible genes such as interferon regulatory factor 9 (IRF9), IRF5, IFN-stimulated gene 15 (ISG15) and toll-like receptor 3 (TLR3) are in fact, p53 direct transcriptional targets. These findings indicate that p53 may play a key role in antiviral innate immunity by both inducing apoptosis in response to viral infection, and enforcing the type I IFN response, and provide a new insight into the evolutionary reasons why many viruses encode p53 antagonistic proteins.
Collapse
Affiliation(s)
- Carmen Rivas
- Centro Nacional de Biotecnologia, CSIC, Darwin 3, Campus Universidad Autónoma, Madrid 28049, Spain; E-Mail: (C.R.)
| | - Stuart A. Aaronson
- Department of Oncological Sciences, Mount Sinai School of Medicine, One Gustave L. Levy Place Box 1130, New York, NY 10029, USA; E-Mail: (S.A.A.)
| | - Cesar Munoz-Fontela
- Department of Oncological Sciences, Mount Sinai School of Medicine, One Gustave L. Levy Place Box 1130, New York, NY 10029, USA; E-Mail: (S.A.A.)
| |
Collapse
|
11
|
Rölle A, Olweus J. Dendritic cells in cytomegalovirus infection: viral evasion and host countermeasures. APMIS 2009; 117:413-26. [PMID: 19400865 DOI: 10.1111/j.1600-0463.2009.02449.x] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Human cytomegalovirus (HCMV) is a beta-herpesvirus that infects the majority of the population during early childhood and thereafter establishes life-long latency. Primary infection as well as spontaneous reactivation usually remains asymptomatic in healthy hosts but can, in the context of systemic immunosuppression, result in substantial morbidity and mortality. HCMV counteracts the host immune response by interfering with the recognition of infected cells. A growing body of literature has also suggested that the virus evades the immune system by paralyzing the initiators of antiviral immune responses--the dendritic cells (DCs). In the current review, we discuss the effects of CMV (HCMV and murine CMV) on various DC subsets and the ensuing innate and adaptive immune responses. The impact of HCMV on DCs has mainly been investigated using monocyte-derived DCs, which are rendered functionally impaired by infection. In mouse models, DCs are targets of viral evasion as well, but the complex cross-talk between DCs and natural killer cells has, however, demonstrated an instrumental role for DCs in the control and clearance of viral infection. Fewer studies address the role of peripheral blood DC subsets, plasmacytoid DCs and CD11c+ myeloid DCs in the response against HCMV. These DCs, rather than being paralyzed by HCMV, are largely resistant to infection, mount a vigorous first-line defense and induce T-cell responses to the virus. This possibly provides a partial explanation for an intriguing conundrum: the highly efficient control of viral infection and reactivation in immunocompetent hosts in spite of multi-layered viral evasion mechanisms.
Collapse
Affiliation(s)
- Alexander Rölle
- Department of Immunology, Institute for Cancer Research, The Norwegian Radium Hospital, Oslo University Hospital, University of Oslo, Oslo, Norway.
| | | |
Collapse
|
12
|
Varani S, Frascaroli G, Landini MP, Söderberg-Nauclér C. Human cytomegalovirus targets different subsets of antigen-presenting cells with pathological consequences for host immunity: implications for immunosuppression, chronic inflammation and autoimmunity. Rev Med Virol 2009; 19:131-45. [DOI: 10.1002/rmv.609] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
|
13
|
Lleo A, Selmi C, Invernizzi P, Podda M, Coppel RL, Mackay IR, Gores GJ, Ansari AA, Van de Water J, Gershwin ME. Apotopes and the biliary specificity of primary biliary cirrhosis. Hepatology 2009; 49:871-9. [PMID: 19185000 PMCID: PMC2665925 DOI: 10.1002/hep.22736] [Citation(s) in RCA: 149] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
UNLABELLED Primary biliary cirrhosis (PBC) is characterized by antimitochondrial antibodies (AMAs), directed to the E2 component of the pyruvate dehydrogenase complex (PDC-E2). Notwithstanding the presence of mitochondria in virtually all nucleated cells, the destruction in PBC is limited to small intrahepatic bile ducts. The reasons for this tissue specificity remain unknown, although biliary epithelial cells (BECs) uniquely preserve the PDC-E2 epitope following apoptosis. Notably, PBC recurs in an allogeneic transplanted liver, suggesting generic rather than host PBC-specific susceptibility of BEC. We used cultured human intrahepatic BECs (HIBECs) and other well-characterized cell lines, including, HeLa, CaCo-2 cells, and nontransformed human keratinocytes and bronchial epithelial cells, to determine the integrity and specific localization of PDC-E2 during induced apoptosis. All cell lines, both before and after apoptosis, were tested with sera from patients with PBC (n = 30), other autoimmune liver and rheumatic diseases (n = 20), and healthy individuals (n = 20) as well as with a mouse monoclonal antibody against PDC-E2 and AMA with an immunoglobulin A isotype. PDC-E2 was found to localize unmodified within apoptotic blebs of HIBECs, but not within blebs of various other cell lineages studied. The fact that AMA-containing sera reacted with PDC-E2 on apoptotic BECs without a requirement for permeabilization suggests that the autoantigen is accessible to the immune system during apoptosis. CONCLUSION Our data indicate that the tissue (cholangiocyte) specificity of the autoimmune injury in PBC is a consequence of the unique characteristics of HIBECs during apoptosis and can be explained by exposure to the immune system of intact immunoreactive PDC-E2 within apoptotic blebs.
Collapse
Affiliation(s)
- Ana Lleo
- Division of Rheumatology, Allergy, and Clinical Immunology, University of California at Davis, Davis, CA, USA, Division of Internal Medicine and Liver Unit, San Paolo School of Medicine, University of Milan, Milan, Italy
| | - Carlo Selmi
- Division of Rheumatology, Allergy, and Clinical Immunology, University of California at Davis, Davis, CA, USA, Division of Internal Medicine and Liver Unit, San Paolo School of Medicine, University of Milan, Milan, Italy
| | - Pietro Invernizzi
- Division of Rheumatology, Allergy, and Clinical Immunology, University of California at Davis, Davis, CA, USA, Division of Internal Medicine and Liver Unit, San Paolo School of Medicine, University of Milan, Milan, Italy
| | - Mauro Podda
- Division of Internal Medicine and Liver Unit, San Paolo School of Medicine, University of Milan, Milan, Italy
| | - Ross L. Coppel
- Department of Medical Microbiology, Monash University, Melbourne, Australia
| | - Ian R. Mackay
- Department of Biochemistry and Molecular Biology, Monash University, Melbourne, Australia
| | - Gregory J. Gores
- Division of Gastroenterology and Hepatology, Mayo Clinic College of Medicine, Rochester, MN, USA
| | - Aftab A. Ansari
- Department of Pathology, Emory University School of Medicine, Atlanta, GA, USA
| | - Judy Van de Water
- Division of Rheumatology, Allergy, and Clinical Immunology, University of California at Davis, Davis, CA, USA
| | - M. Eric Gershwin
- Division of Rheumatology, Allergy, and Clinical Immunology, University of California at Davis, Davis, CA, USA
| |
Collapse
|
14
|
Abstract
Dendritic cells are the most potent antigen-presenting cells of the mammalian immune system and are central to the initiation and maintenance of the adaptive immune response. They are crucial for the presentation of antigen to T cells and B cells, as well as the induction of chemokines and proinflammatory cytokines, which orchestrate the balance of the cell-mediated (Th1) and antibody (Th2) response. This ability of dendritic cells to present antigen and release chemokines and cytokines also bridges the innate and adaptive immune responses by driving T cell activation. These cells thus possess key immunological functions that make them the front line of defence for the targeting and clearance of any invading pathogen and, as such, they underpin the host immune response to infection. For efficient infection, invading pathogens often need to overcome these sentinel immune functions. It is therefore not surprising that pathogens have evolved numerous mechanisms to target dendritic cell functions directly or indirectly during infection, and at least one herpesvirus--human cytomegalovirus--has evolved a life cycle that hijacks dendritic cells for its long-term persistence in the infected host.
Collapse
|
15
|
Lleo A, Selmi C, Invernizzi P, Podda M, Gershwin ME. The consequences of apoptosis in autoimmunity. J Autoimmun 2008; 31:257-62. [PMID: 18513925 DOI: 10.1016/j.jaut.2008.04.009] [Citation(s) in RCA: 102] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The clearance of apoptotic cells is a highly regulated mechanism, normally associated with anti-inflammatory response. During early stages of apoptosis the cell is promptly recognized and engulfed by professional phagocytes or tissue cells to avoid the outflow of intracellular content and limit the immunological reaction against released antigens. However, increasing evidences suggest that impairment in the uptake of apoptotic cell debris is linked to the development of autoimmunity. In fact, autoantigens have been demonstrated to be content within apoptotic bodies and apoptotic cells seems to be critical in the presentation of antigens, activation of innate immunity and regulation of macrophage cytokine secretion. We herein review the known mechanisms for regulating the uptake of the products of apoptosis in the development of autoimmunity.
Collapse
Affiliation(s)
- Ana Lleo
- Division of Rheumatology, University of California, Davis, CA, USA
| | | | | | | | | |
Collapse
|
16
|
Martin H, Mandron M, Davrinche C. Interplay between human cytomegalovirus and dendritic cells in T cell activation. Med Microbiol Immunol 2008; 197:179-184. [PMID: 18264717 DOI: 10.1007/s00430-008-0079-0] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2007] [Indexed: 10/22/2022]
Abstract
Control of human cytomegalovirus (HCMV) infection and prevention of associated diseases in immunocompetent hosts are ensured mainly by CD8+ T cells, in spite of numerous viral tricks to impair antigen presentation and activation of T cells. At sites of primary infection, dendritic cells (DCs) are in the forefront to ensure capture of viral antigens and their capacity to bypass the effects of viral immunoevasins is crucial in moulding CD8+ T cell repertoire. In HCMV-seropositive donors, the spectrum of CD8+ T cells specificities was shown to include immediate-early (IE), early (E) and late (L) gene products, a surprising finding if we consider that expression of immunoevasins could paralyse infected DCs from the IE phase of infection. In the present report, we suggest that uninfected dendritic cells could acquire HCMV-antigens derived from input virus or neosynthesis, either in soluble forms or in association with infected dead cells resulting from death-ligand-mediated apoptosis and necrosis. Activation of naïve CD8+ T cells could then occur in lymph nodes through cross-presentation by antigen-loaded DCs, providing an explanation for shape and size of the memory compartment.
Collapse
Affiliation(s)
- Hélène Martin
- Centre de Physiopathologie de Toulouse Purpan, INSERM, U563, Toulouse 31300, France
| | | | | |
Collapse
|